7 Common Vitamin Deficiencies

Even low-level vitamin deficiencies can sap energy, diminish immune function, and lead to mood swings and brain fog. Here’s a look at some of the most common deficiencies—and what you can do about them.

What causes nutrient deficiencies?

It’s not always a matter of just failing to eat a balanced diet. Long-term use of proton-pump inhibitors (PPIs), cholesterol-lowering statins, diuretics, and other medications can interfere with the body’s ability to produce, absorb, or utilize crucial nutrients. Celiac disease, inflammatory bowel disease such as Crohn’s disease, and many other digestive problems can reduce absorption of nutrients and also lead to deficiencies. And other factors, such as chronic dieting, excessive coffee or alcohol intake, and stress, can deplete vitamins and minerals, fast.

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If you’re eating right, but still not thriving, you may not be truly nourished. But the good news is that it’s easy to remedy these issues and get yourself back to vibrant. Here’s how.

1. Vitamin D

This fat-soluble vitamin is essential for bone strength, immune function, brain health, and mood. But unless you spend time outside sans sunscreen, you may be deficient. In addition, people with dark skin, those who live in northern climates, and people who are obese are more likely to be deficient in vitamin D. Deficiencies aren’t obvious, and symptoms may take years to manifest. Signs that you’re lacking in D include poor immune function, fatigue, muscle weakness, bone loss, and depression.

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Food sources: It’s hard to get significant vitamin D from food—cod liver and fatty fish such as salmon and sardines are the only good sources. If you suspect you may be lacking in D, get your levels tested. For more information on how to make sure you're getting enough D, visit the Vitamin D Council at vitamindcouncil.org.

Supplement facts: Because vitamin D is hard to get from food, you’ll probably need to supplement if you’re low in it. Choose vitamin D3 (cholecalciferol), the form your body naturally makes when it’s exposed to sunlight.

2. Magnesium

Critical for bone and tooth health, this mineral is also involved in detoxifying heavy metals and other toxins from the body, and it plays a part in hundreds of enzymatic reactions. But because it’s depleted by antibiotics, cortisone, painkillers, stress, and excess sugar consumption, some 48 percent or more of Americans may be lacking this critical nutrient. Low levels are marked by irregular heartbeat, muscle cramps, restless leg syndrome, cravings for chocolate, and fatigue. Long-term deficiencies can lead to osteoporosis, heart disease, diabetes, high blood pressure, and stroke.

Food sources: Nuts, seeds, leafy greens, dark chocolate, sea vegetables, beans, and whole grains are the best food sources. Because most foods today are lacking in magnesium and other minerals as a result of soil depletion, supplements can help.

Supplement facts: The best choices are magnesium amino acid chelates, magnesium citrate, and magnesium threonate, all of which have high levels of absorption. Avoid magnesium oxide, a cheap form of the mineral that’s poorly absorbed. Soaking in Epsom salt baths—high in magnesium sulfate, which is absorbed in small amounts into the body via the skin—can also increase your body’s levels of magnesium.

3. Omega-3 fats

These healthy fats are critical for heart and brain health, and to protect against inflammation. But because they exist in a balance with omega-6 fats—prevalent in the processed American diet—most people tend to be deficient in omega-3s. Low levels manifest in dry, flaky skin; fatigue; reduced immune function; and mood disorders. Long-term deficiencies can lead to inflammation, depression, heart disease, Alzheimer’s disease, cancer, and other serious diseases.

Food sources: Sardines, salmon, mackerel, and tuna are the best sources of EPA and DHA, the types of omega-3 fats used by the body. Vegetarian foods such as walnuts, flax, and chia seeds contain a type of omega-3 fats called ALA, which the body converts into usable forms. Unfortunately, the conversion rate is very low, so if you don’t eat fish, it’s wise to consider a supplement.

Supplement facts: Because omega-3 fats are prone to oxidation—doing more harm than good if you take them—it’s critical to choose a high-quality oil. It should smell like the ocean, but not like old or rotten fish—a strong lemon or lime scent may be an attempt to mask fishy odors. Krill oil contains astaxanthin, an antioxidant that prevents the fats from oxidizing, but is lower in total omega-3 fats compared to fish oil. Always choose a fish oil that meets international standards for toxins to be sure it’s free of heavy metals.

4. Iron

This essential mineral is responsible for transporting oxygen to cells and regulating cell growth and differentiation. Deficiencies are common, especially in preschool children, pregnant women, vegetarians, vegans, and women of child-bearing years. Low-grade iron deficiency leads to anemia, and manifests in weakness, fatigue, impaired immune response, and diminished brain function.

Food sources: There are actually two types of iron. Heme iron, found only in animal foods, is especially well-absorbed and utilized by the body—one reason vegans and vegetarians are more susceptible to iron deficiencies. The best sources of heme iron are red meat, dark-meat poultry, organ meats, mussels, oysters, clams, and sardines. Non-heme iron is found in both animal and plant foods. It’s more common, but harder for the body to absorb. You’ll find non-heme iron in beans, legumes, seeds, greens, and dried fruit. Eat them with bell peppers, strawberries, oranges, and other foods high in itamin C, or with acids such as vinegars and tomatoes, to enhance the body’s ability to absorb non-heme iron.

Supplement facts: If you suspect that you’re anemic, be cautious with supplementing, as too much iron can be toxic. The body is limited in its ability to excrete iron, and when levels build up, it can damage cells and increase the risk of heart disease. Ask your health care provider to test your iron levels before supplementing.

5. Iodine

This vital mineral regulates thyroid function and the production of thyroid hormones, necessary for growth, metabolic rate, bone health, and brain development. Deficiencies are common, especially in people who avoid salt or use sea salt, and in vegans and vegetarians. Deficiencies can lead to goiter (enlarged thyroid gland), weight gain and obesity, cognitive impairment, psychiatric disorders, and fibromyalgia. Some newer research also links iodine deficiency to breast cancers and high rates of fibrocystic breast disease.

Food sources: The best dietary source of iodine is seaweed; as little as ¼ tsp. of most types of kelp powder will more than meet the RDI. Other good sources include seaweed, fish, shellfish, milk, and eggs. Table salt has varying levels of added iodine, so don’t count on it for your iodine content.

Supplement facts: Like iron, iodine is toxic in high doses, so check with your health care provider first. If you do supplement, choose iodide, which is iodine in its ionized form, and don’t take more than the recommended dosage.

6. Vitamin E

This powerful antioxidant prevents free radical damage, protects the heart, reduces the risk for Alzheimer's disease, and prevents cancer. In one landmark study, vitamin E (alpha tocopherol) levels were associated with a significant reduction in overall mortality, as well as a 21–42 percent reduced risk of prostate cancer, stroke, lung cancer, and respiratory disease. Even so, as many as 93 percent of American men and 96 percent of American women don’t consume the recommended dietary allowance of vitamin E.

Supplement facts: Vitamin E is actually a group of eight primary antioxidant compounds, made up of four groups of tocopherols and four groups of tocotrienols. The best supplements are full-spectrum compounds that combine a mixture of tocopherols and tocotrienols. Look for “d” forms, such as d-alpha tocopherol, rather than “dl” forms.

7. Vitamin K

This fat-soluble vitamin is critical in building strong bones, protecting the heart, and ensuring proper brain function. Vitamin K is produced in the intestines, and the amount of vitamin K the body can absorb from the diet is directly related to gut health and probiotics—so if you suffer from chronic digestive difficulties or bowel problems, you may be at risk. Cholesterol-lowering statins and extended periods of antibiotics also compromise the gut and make it difficult for the body to absorb adequate amounts of vitamin K. Low levels of vitamin K can manifest as bleeding and bruising easily, tooth decay, and weakened bones. Long-term deficiencies can lead to osteoporosis, cardiovascular disease, and cancer, as well as a shorter life span. In one recent study, people with the highest intake of vitamin K were 36 percent less likely to die from any cause, compared to those with the lowest intake.

Food sources: There are two main types of vitamin K: K1, found in spinach, cabbage, leafy greens, eggs, and fish, and K2, found in grass-fed animal products, fermented foods such as sauerkraut or natto, and certain cheeses, including Brie.

Supplement facts: The body needs both K1 and K2, although K2 appears to have the most pronounced effects. MK7, or menaquinone-7, is an especially bioavailable type of K2.

How Drugs Deplete Your Nutrients

Some over-the-counter and prescription medications can deplete your body of key nutrients. Here are a few of the most common drug-nutrient depletions:

Is it the saltiness of potato chips or the rich flavor of chocolate? Whatever you're hankering for, it may be your body's way of letting you know you're missing valuable nutrients. Here's how to decode your cravings.